   :scp-options       a scp options string
   :rsync-options    a rsync options string.
   :user                    global user for cluster,if cluster do not have :user ,it will use this by default.
+  :parallel               if to execute task on remote machines in parallel,default is false
 
   Example:
         (set-options! :ssh-options \"-o ConnectTimeout=3000\")

                   task-name (keyword (second args))
                   task-args (next (next args))
                   cluster (cluster-name @clusters)
                   parallel (:parallel cluster)
                   user (:user cluster)
                   addresses (:addresses cluster)
                   clients (:clients cluster)

      (alength p)
      3)))

(defn- is-parallel? [cluster]
  (or (:parallel cluster) (:parallel @*global-options*)))

(defn do-begin [args]
  (when-exit (< (count args) 2)
             "Please offer cluster and task name"
